Movement capability for buttonless touchpads and forcepads

ABSTRACT

A system and method for enabling an entire touchpad surface to mechanically move if sufficient force is used to press on the touchpad to perform a mouse click function, such as a right click or a left click, when the touchpad is mechanically buttonless, such as a forcepad, in order to provide haptic feedback on a touchpad that otherwise has none.

BACKGROUND OF THE INVENTION

Field Of the Invention

This invention relates generally to touch sensors. Specifically, theinvention pertains to a system and method for enabling an entiretouchpad surface to mechanically move if sufficient force is used topress on the touchpad to perform a mouse click function, such as a rightclick or a left click.

Description of Related Art

There are several designs for capacitance sensitive touch sensors whichmay take advantage of a system and method for providing mechanicalmovement of a touchpad that is buttonless. It is useful to examine theunderlying technology of the touch sensors to better understand how anycapacitance sensitive touchpad can take advantage of the presentinvention.

The CIRQUE® Corporation touchpad is a mutual capacitance-sensing deviceand an example is illustrated as a block diagram in FIG. 1. In thistouchpad 10, a grid of X (12) and Y (14) electrodes and a senseelectrode 16 is used to define the touch-sensitive area 18 of thetouchpad. Typically, the touchpad 10 is a rectangular grid ofapproximately 16 by 12 electrodes, or 8 by 6 electrodes when there arespace constraints. Interlaced with these X (12) and Y (14) (or row andcolumn) electrodes is a single sense electrode 16. All positionmeasurements are made through the sense electrode 16.

The CIRQUE® Corporation touchpad 10 measures an imbalance in electricalcharge on the sense line 16. When no pointing object is on or inproximity to the touchpad 10, the touchpad circuitry 20 is in a balancedstate, and there is no charge imbalance on the sense line 16. When apointing object creates imbalance because of capacitive coupling whenthe object approaches or touches a touch surface (the sensing area 18 ofthe touchpad 10), a change in capacitance occurs on the electrodes 12,14. What is measured is the change in capacitance, but not the absolutecapacitance value on the electrodes 12, 14. The touchpad 10 determinesthe change in capacitance by measuring the amount of charge that must beinjected onto the sense line 16 to reestablish or regain balance ofcharge on the sense line.

The system above is utilized to determine the position of a finger on orin proximity to a touchpad 10 as follows. This example describes rowelectrodes 12, and is repeated in the same manner for the columnelectrodes 14. The values obtained from the row and column electrodemeasurements determine an intersection which is the centroid of thepointing object on or in proximity to the touchpad 10.

In the first step, a first set of row electrodes 12 are driven with afirst signal from P, N generator 22, and a different but adjacent secondset of row electrodes are driven with a second signal from the P, Ngenerator. The touchpad circuitry 20 obtains a value from the sense line16 using a mutual capacitance measuring device 26 that indicates whichrow electrode is closest to the pointing object. However, the touchpadcircuitry 20 under the control of some microcontroller 28 cannot yetdetermine on which side of the row electrode the pointing object islocated, nor can the touchpad circuitry 20 determine just how far thepointing object is located away from the electrode. Thus, the systemshifts by one electrode the group of electrodes 12 to be driven. Inother words, the electrode on one side of the group is added, while theelectrode on the opposite side of the group is no longer driven. The newgroup is then driven by the P, N generator 22 and a second measurementof the sense line 16 is taken.

From these two measurements, it is possible to determine on which sideof the row electrode the pointing object is located, and how far away.Using an equation that compares the magnitude of the two signalsmeasured then performs pointing object position determination.

The sensitivity or resolution of the CIRQUE® Corporation touchpad ismuch higher than the 16 by 12 grid of row and column electrodes implies.The resolution is typically on the order of 960 counts per inch, orgreater. The exact resolution is determined by the sensitivity of thecomponents, the spacing between the electrodes 12, 14 on the same rowsand columns, and other factors that are not material to the presentinvention. The process above is repeated for the Y or column electrodes14 using a P, N generator 24

Although the CIRQUE® touchpad described above uses a grid of X and Yelectrodes 12, 14 and a separate and single sense electrode 16, thesense electrode can actually be the X or Y electrodes 12, 14 by usingmultiplexing.

It should be understood that use of the term “touch sensor” throughoutthis document may be used interchangeably with “forcepad”, “buttonlesstouchpad”, “proximity sensor”, “touch and proximity sensor”, “touchpanel”, “touchpad” and “touch screen”.

Buttonless touchpads and forcepads may be touch sensors that may notprovide a user friendly haptic sensation of a mechanical “click” whenpressed. While the touch sensors are still able to provide thefunctionality of the mouse click, they nevertheless may fail to providetactile feedback that may not be necessary, but which may be desirableto users.

Furthermore, many touch sensors do not allow the user to perform amechanical click, right or left, at a top portion of the touchpad. Thisis an inherent design issue due to the mechanical button(s) beingmounted at the bottom area of the underside of the touch sensor surfacebecause the touch sensor is hinged near the upper area of the touchpad.It may be that these types of designs allow about 80% of the touchsensor to be used for “clicking” because a mechanical click on the upper20% of the pad is either not possible or requires excessive force.

There may be some touch sensors that do not allow any mechanicalmovement, but instead create an “artificial” click-type response using amotor when the user presses anywhere on the touch sensor, such as in aforcepad. There may also be other forcepad designs that create anaudible “click” sound as the user presses on a touch sensor which sensesmechanical pressure. However, these touch sensor also lack mechanicalmovement of the touch sensor itself.

BRIEF SUMMARY OF THE INVENTION

In a first embodiment, the present invention is a system and method forenabling an entire touchpad surface to mechanically move if sufficientforce is used to press on the touchpad to perform a mouse clickfunction, such as a right click or a left click, when the touchpad ismechanically buttonless, such as a forcepad, in order to provide hapticfeedback on a touch sensor that otherwise has none.

These and other objects, features, advantages and alternative aspects ofthe present invention will become apparent to those skilled in the artfrom a consideration of the following detailed description taken incombination with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram of operation of a touchpad that is found inthe prior art, and which is adaptable for use in the present invention.

FIG. 2 is a picture of a top view of a substrate and touch sensordisposed thereon, the substrate having four flex arms on each corner ofthe touch sensor.

FIG. 3 is a perspective view of the bottom of a substrate showing amechanical switch disposed in the center of the substrate to provide amechanical switch when the touch sensor is pressed.

FIG. 4 is a view from an edge of the touch sensor showing that thesubstrate is only supported by the housing at a distal end of each ofthe four flex arms.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made to the drawings in which the various elementsof the present invention will be given numerical designations and inwhich the invention will be discussed so as to enable one skilled in theart to make and use the invention. It is to be understood that thefollowing description is only exemplary of the principles of the presentinvention, and should not be viewed as narrowing the claims whichfollow.

FIG. 2 is a picture of a first embodiment of the touch sensor 30. Thetouch sensor 30 has several features that should be explained. The touchsensor 30 may be disposed on a substrate that is formed as a continuouspiece of material. A first feature of the touch sensor 30 may be thefour flex arms 32 that may suspend the touch sensor within a housing,not shown. The substrate of the touch sensor 30 may be manufactured froma single sheet of flexible material as shown in this first embodiment.For example, the substrate may be comprised of printed circuit board(PCB). The PCB may be sufficiently flexible to enable the four flex arms32 to provide the desired mechanical action of the touch sensor 30.

In this first embodiment, the four flex arms 32 are shown with a hole 34at the distal end of each flex arm. The hole 34 may be used to positionand hold the touch sensor 30 in place within a housing. For example, thehole 34 may be positioned over a projection on the housing on which thehole may be positioned. Applying a force to any portion of the sensorportion 36 of the touch sensor 30, may result in the flexing of the fourflex arms 32 where the flex arms are attached to the four corners of thetouch sensor.

Alternatively, the four flex arms 32 may be mechanically attached to thetouch sensor 30 instead of being an integral part of the structure ofthe touch sensor, and may still provide the flexibility needed for thetouch sensor to be mechanically manipulated by a force applied to thetouch sensor.

The length of each of the four flex arms 32 may be the same or they mayvary. The four flex arms 32 may vary in width and length. The four flexarms may or may not have the hole 34 for positioning.

In this first embodiment, the touch sensor 30 may include four smalltabs 38. While the four flex arms 32 may be disposed on the short sides40 of the touch sensor 30, the tabs 38 may be disposed on the long sides42 of the touch sensor. The tabs 38 may function to prevent undesiredmovement of the touch sensor 30. For example, the four tabs 38 may bepivot points that may prevent the touch sensor 30 from lifting out ofthe housing and to instead assist the touch sensor in moving downwardinto a depression in the housing when a force is applied to the topsurface 44 of the touch sensor.

For example, when pressing on a far left side of the touch sensor 30,the far right side of the touch sensor may try to lift out of thehousing. However, if the tabs 38 are actually underneath an edge of thehousing, then the housing itself may prevent the touch sensor 30 fromlifting out of the housing.

The specific location of the four tabs 38 along the long side 42 may bechanged in order to obtain a different depth of movement of the touchsensor 30 when a force is applied to the surface. Accordingly, theposition of the four tabs 38 along the long side 42 may be changed inorder to achieve different movement characteristics of the touch sensor30 when a force is applied.

FIG. 3 is a partial perspective view of a bottom surface 46 of the touchsensor 30. In this first embodiment, the bottom surface 46 shows aswitch 48 disposed in approximately a center of the touch sensor 30. Theswitch 48 may provide a mechanical click function. The mechanical clickfunction may be a haptic movement, a clicking sound, or both.

FIG. 4 is a view of the touch sensor 30 and a supporting structure 50from a side or edge. The touch sensor 30 is shown as supported by theposts 52 of the supporting structure 50 on the flex arms 32. The flexarms 32 may be the only part of the touch sensor 30 to be in contactwith the supporting structure 50. When a force is applied to the topsurface 44 of the touch sensor 30, the touch sensor may travel downward,while supported by the four flex arms 32, until the switch 48 on thebottom surface 46 of the touch sensor makes contact with the bottom of adepression in the housing.

One aspect of the first embodiment is that a force may be applied at anylocation on the top surface 44 of the touch sensor 30 and still causethe entire touch sensor to move in the direction that the force isapplied. However, the touch sensor 30 may be tilted so that some areasof the touch sensor moves further than other portions of the touchsensor. Nevertheless, all of the top surface 44 of the touch sensor 30may move down into the housing as the force is applied. Movementcontinues until the force is removed or until the center switch 48 makescontact with the housing, preventing further movement of the touchsensor 30.

It is an aspect of the touch sensor 30 that the material used for thetouch sensor will be flexible enough so that the touch sensor may returnto an unflexed or rest position when the force is not being applied.

One advantage of the first embodiment and the use of four flex arms 32may be that the stress on the touch sensor 30 at the joint 54 (seeFIG. 1) between the touch sensor and the four flex arms may be moreevenly distributed across the joints of the touch sensor. Thus, it maybe easier to cause the mechanical movement of the touch sensor 30.

While it is desirable to have the joints 54 flex on the touch sensor 30,it may be undesirable to have the top surface 44 of the touch sensor toflex when a force is applied to perform a click function. One advantageof the first embodiment is that a material used to prevent flexing ofthe surface of the touch sensor 30 may not have to be as rigid if onlyusing only two flex arms 32 because the touch sensor may now move moreeasily with four flex arms. Alternatively, a thickness of the materialused to prevent flexing of the touch sensor 30 may not have to be asthick and thereby increasing sensitivity of the touch sensor.

Another aspect of the first embodiment is that a haptics motor may beused to provide additional movement of the touch sensor 30. Theadditional movement of the touch sensor 30 may be a function of theamount of force or pressure that is applied to the touch sensor. Thehaptics motor may therefore provide an additional degree of movement ofthe touch sensor 30. The haptics motor may be located at any locationadjacent to or directly on the touch sensor 30 as needed.

Another aspect of the first embodiment may be a mechanical spring biasfeature. The spring bias feature may be used to apply a force to thebottom surface 46 of the touch sensor 30 and hold it away from thehousing. The touch sensor 30 may be held within the housing by the fourtabs 38.

It is noted that a spring mounting platform may be provided having aramped surface and an opposing feature that bends the spring to form apreloaded condition. The touch sensor 30 may be pushed against an insidebezel surface of the housing when the touch sensor 30 is at a restposition when no downward force on the top surface 44 is being applied.

Although only a few example embodiments have been described in detailabove, those skilled in the art will readily appreciate that manymodifications are possible in the example embodiments without materiallydeparting from this invention. Accordingly, all such modifications areintended to be included within the scope of this disclosure as definedin the following claims. It is the express intention of the applicantnot to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any ofthe claims herein, except for those in which the claim expressly usesthe words ‘means for’ together with an associated function.

What is claimed is:
 1. A method for providing mechanical movement of theentire surface of a touch sensor when force is applied, said methodcomprising the steps of: providing a substrate for a touch sensor, thesubstrate forming a rectangular surface, the substrate having four flexarms, each one of the four flex arms being located to a different cornerof the rectangular surface and flexing at a joint between the substrateand the four flex arms; providing a housing for the touch sensor, thehousing supporting the touch sensor at an end of each of the four flexarms; providing a touch sensor on the surface of the substrate, whereinthe touch sensor is a buttonless touch sensor having no mechanicalbuttons for performing mouse click functions; applying a force againstthe rectangular top surface of the touch sensor and causing the topsurface of the touch sensor to move within the housing to provide hapticfeedback to the user while the substrate is flexing at the joint of eachof the four flex arms, to thereby provide movement to the buttonlesstouch sensor.
 2. The method as defined in claim 1 wherein the methodfurther comprises the steps of: providing a mechanical switch on abottom surface of the substrate, wherein movement of the substrate isstopped when the mechanical switch makes contact with the housing; andproviding a mechanical click action when the mechanical switch makescontact with the housing.
 3. The method as defined in claim 2 whereinthe method further comprises the step of providing an audible sound withthe mechanical click action.
 4. The method as defined in claim 1 whereinthe method further comprises the step of only supporting the substrateat a distal end of each of the four flex arms.
 5. The method as definedin claim 1 wherein the method further comprises the step of returningthe substrate to a rest position when the force is removed from the topsurface of the touch sensor.
 6. The method as defined in claim 1 whereinthe method further comprises providing more even distribution of stresson the four flex arms of the touch sensor by disposing the four flexarms near each corner of the substrate.
 7. The method as defined inclaim 6 wherein the method further comprises the step of preventingflexing of the touch sensor on the substrate by providing a material onthe substrate that prevents flexing.
 8. The method as defined in claim 7wherein the method further comprises increasing sensitivity of the touchsensor by reducing a thickness of the material used to prevent flexingof the substrate.
 9. The method as defined in claim 1 wherein the methodfurther comprises the step of providing a haptic motor that is coupledto the touch sensor to thereby increase haptic feedback of the touchsensor when a force is applied to the touch sensor that is sufficient tocause the touch sensor to move.
 10. A system for providing mechanicalmovement of the entire surface of a touch sensor when force is applied,said system comprised of: a substrate for a touch sensor, the substrateforming a rectangular surface; four flex arms wherein each one of thefour flex arms is coupled to a different corner of the rectangularsurface and flexing at a joint between the substrate and the four flexarms; a housing for the touch sensor, the housing supporting the touchsensor at a distal end of each of the four flex arms; and a touch sensordisposed on the surface of the substrate, wherein the touch sensor is abuttonless touch sensor having no mechanical buttons for performingmouse click functions, and wherein applying a force against therectangular surface of the touch sensor causes the top surface of thetouch sensor to move within the housing to provide haptic feedback tothe user while the substrate is flexing at the joint of each of the fourflex arms, to thereby provide movement to the buttonless touch sensor.11. The system as defined in claim 10 wherein the system is furthercomprised of: a mechanical switch disposed on a bottom surface of thesubstrate, wherein movement of the substrate is stopped when themechanical switch makes contact with the housing; and a mechanical clickaction performed when the mechanical switch makes contact with thehousing.
 12. The system as defined in claim 11 wherein the system isfurther comprised an audible sound with the mechanical click action. 13.The system as defined in claim 10 wherein the system is furthercomprised of supporting the substrate at a distal end of each of thefour flex arms.
 14. The system as defined in claim 10 wherein the systemis further comprised of even distribution of stress on the substrate byhaving the four flex arms disposed near each corner of the substrate.15. The system as defined in claim 14 wherein the system is furthercomprised of providing a material on the substrate that preventsflexing.
 16. The system as defined in claim 15 wherein the system isfurther comprised of increasing sensitivity of the touch sensor byreducing a thickness of the material used to prevent flexing of thesubstrate.
 17. The system as defined in claim 10 wherein the system isfurther comprised of a haptic motor to increase haptic feedback of thetouch sensor when a force is applied to the touch sensor that issufficient to cause the touch sensor to move.